07 Nov Whendee Young
Whendee Young brings together environmental engineering, science and stakeholder engagement to deliver major ecological restoration projects in South Australian water catchments. Her focus over the past ten years has been wetland and floodplain restoration in the South Australian Murray Darling Basin. Working with community and all levels of government she combines her technical knowledge across hydrology, hydrogeology, riverine ecology and engineering to find innovative solutions for restore these important ecosystems and build resilience into the future.
Managed Aquifer Recharge to Support Ecological Restoration in the Katarapko Floodplain
The Katarapko Floodplain located in the South Australian Murray-Darling Basin has significant cultural, social, recreational and environmental value, with majority of the floodplain in the Murray River National Park. The health of the floodplain has been in decline for several decades because of river regulation and water over allocation. This has been exacerbated by the Millennium Drought, 2000 to 2010.
As part of the South Australian Riverland Floodplain Integrated Infrastructure Program (SARFIIP), a blocking bank and regulators will be constructed on the Katarapko Floodplain. The aim of building this infrastructure is to provide a more natural pattern of freshwater inundation frequency and duration over approximately 1,300 ha. Inundation of the floodplain is anticipated to provide some vertical infiltration of low salinity surface water, creating and replenishing the freshwater lenses, improving soil moisture content, and reducing soil salinity. However, groundwater level rise in response to managed inundation events may mobilise highly saline groundwater, presenting a threat to existing freshwater lenses. This threat may lead to vegetation benefits may not be fully realised due to localised potential increases in soil salinization from raised groundwater levels.
Injection of freshwater using managed aquifer recharge into the shallow groundwater system is being trialled on the Katarapko Floodplain as an option to expand existing zones of lower salinity groundwater and mitigate against the possible displacement of the existing freshwater lenses. This paper presents the initial results of the managed aquifer recharge trial aimed at increasing the understanding of the technical feasibility of injecting river water into the floodplain; the effectiveness of the injected water in freshening the groundwater noticeably and extensively; the timing of changes; and the impact on surrounding groundwater gradients.
Diagram Source: DEW & WGA 2019